A camera system includes a camera body having an in-body motor; an interchangeable lens having an in-lens motor, the interchangeable lens being detachable from the camera body; a focusing mechanism for moving a focusing lens group provided in the interchangeable lens in an optical axis direction thereof; a rotational force transmission device which transmits a rotational force of the in-body motor to the focusing mechanism to perform an AF operation in a state where the interchangeable lens is attached to the camera body; an auto-focusing mechanism for driving the focusing mechanism to perform an AF operation by the in-lens motor, independently from the in-body motor; and a one-way clutch which allows transmission of a rotational force of the in-body motor to the in-lens motor while preventing a rotational force of the in-lens motor from being transmitted to the in-body motor.